The present invention relates to the field of optical beam steering.
There are many important applications which call for optical beam steering. One of these applications is free space optical communications, which is important to the telecommunications, cable and satellite television industries. The military is especially interested in free space optical data communication systems which are secure.
Most current optical beam steering systems are mechanically driven systems which are complex, bulky, imprecise and expensive, and require high power to produce desired acceleration of the components thereof. The steering of these systems is relatively slow and imprecise often requiring mechanical stabilization, and such systems are sensitive to vibration and acceleration. Another approach includes the use of deformable micro-mirrors, which operate in response to electro-static field changes. Their speeds have been in the microsecond range and thus are undesirably slow, while the angular mirror deflections are quite small. A non-mechanical approach employs acousto-optic (AO) beam deflection, which is also relatively slow, performing beam deflection in microseconds, and is limited to small angles of beam deflection of a few milliradians. Another approach includes electro-optic beam deflectors which are faster, operating in the nanosecond range, but also have limitations in angular beam deflection in the milliradian range. The Government has expended considerable funds in the development of non-mechanical beam steering systems. To date, most of these approaches have employed optical phased arrays, broadly based upon RF phased array radar systems.
To date, the highest performance results for phased array systems were obtained using liquid-crystal based phased arrays. However, these systems are relatively slow, in the millisecond range, and are limited to small angular deflections of only a few degrees.
Thus, there is a need for alternate approaches employing apparatus which is rugged, and can very rapidly steer light beams accurately in a wide angle of view even up to 360 degrees without mechanical devices with their low speed and angular displacement limitations mentioned hereinabove. Rapid beam deflection, operating at speeds of about one nanosecond are desired.